Great willowherb
Also known as
Hairy willowherb, Great hairy willowherb, Codlins-and-cream, Large-flowered willowherb
Keep this plant’s care guide close at hand.
Get the appAbout Great willowherb
Epilobium hirsutum, commonly called great willowherb, is a vigorous, rhizomatous perennial in the evening-primrose family (Onagraceae). It forms tall, upright clumps 1–2 m high with softly hairy, often reddish stems and sessile, lanceolate leaves with serrated margins arranged opposite or in loose whorls. From mid- to late summer it carries showy, rose-pink to magenta flowers, each with four deeply notched petals and a pale center, followed by long, slender seed capsules that split to release numerous silky-plumed seeds dispersed by wind. Native across much of Europe, western and central Asia, and North Africa, it thrives in damp, nutrient-rich soils along watercourses and disturbed wet ground, and has naturalized in parts of North America and New Zealand. The species is valued by pollinators, attracting bees and hoverflies, but can spread assertively via both seed and creeping rhizomes. In gardens it suits wildlife and wetland plantings, where its moisture-loving nature and striking floral displays can be showcased.
Taxonomy
Properties & Requirements
How to care for Great willowherb
Water
Keep soil consistently moist to wet. Great willowherb tolerates periodic waterlogging and even shallow standing water, making it ideal for pond margins or rain gardens. In the ground, water deeply during dry spells to maintain even moisture; do not allow the root zone to dry out completely. In containers, use a water-retentive mix and water whenever the top 1–2 cm feels moist but not saturated—daily in hot weather. Mulch to reduce evaporation and stabilize moisture.
Light
Full sun to light shade. For best flowering and sturdy stems, provide at least 6 hours of direct sun. It will tolerate partial shade (3–5 hours), especially in consistently wet soils, though flowering may be reduced and stems may lean. In hot, inland climates, filtered afternoon light helps reduce stress if moisture is marginal. Avoid deep shade, which encourages lanky growth and sparse blooms. Air movement is beneficial but not essential.
Nutrients
Great willowherb is not a heavy feeder; it naturally colonizes nutrient-rich, moist soils. In gardens, work in organic matter (well-rotted compost or leaf mold) in spring to enhance moisture retention and fertility. For container-grown plants, use a slow-release, balanced fertilizer once in spring or a half-strength liquid feed monthly during active growth. Avoid excessive nitrogen, which can promote weak, floppy growth and unwanted spread. Mulching annually with compost maintains steady nutrition and supports soil life.
Temperature
A hardy temperate perennial, it overwinters reliably in the ground across cold climates and tolerates freezes to about −20 °C when dormant. Optimal growth occurs between 10–25 °C. In hot summers it remains vigorous if soil stays wet; drought plus heat can cause wilting and premature senescence. No winter protection is needed in most regions; mulch can buffer freeze-thaw in exposed sites. Container plants may need pot insulation to prevent roots from freezing solid.
